Mechanical device



Oct. 22, 1963 D, E. sUTroN 3,107,461

MECHANICAL DEVICE D. E.su1'roN MECHANICAL nEvIcE 4 Sheets-Sheet 3 Filed Nov. 14. 1960 INV EW TOR.

nir 'IIIIIIIIIIIIIIIIA u l l l l 1 l l DONALD E. surrolv Oct. 22, 1963 n. E. suTToN Filed Nov. 14. 1960 IIII MECHANICAL DEVICE 4 Sheets-Sheet 4 INVENIOR DONALD E SUT/'0N A T ORNE YS United States Patent O 3,107,461 MECHANICAL DEVICE Donald E. Sutton, Comstock Township, Kalamazoo County, Mich., assigner to Hammond Machinery Builders, Inc., Kaiamazoo, Mich., a corporation of Michigan Fiied Nov. I4, 196i), Ser. No. 68,827 8 Claims. (Ci. 51-219) This invention relates to a holder for a twist drill grinding operation and particularly to a type thereof having a variety of `adjustments so that it may be accommodated to a wide range of drill sizes and shapes, particularly drills having varying lengths, diameters, relief angles, and point angles.

While previous workers in the field of twist drill grinding have devised almost countless types of devices for holding such drills to be ground, none of them, insofar as I am aware, have been adaptable, without being excessively complex in either or both of construction and operation, to as wide a variety of sizes and types of twist drills as is desirable for meeting commercial requirements. For example, certain types of drill holders are sturdy, relatively inexpensive and simple to operate, but they are limited to only a. single point `angle. Other types of drill holders are supplied with sa wide range of controls and adjustments of various kinds but these are in many cases either too expensive to be generally accepted in the trade, so complicated that most workmen will not use them or they have other deliciencies which limit their acceptability.

Holders limited to single point angle grinding are satisfactory under conditions of high production where drills of a single type or shape are used in sufliciently large numbers that only a single point yangle needs to be considered in connection with a given drill holder. The adjustable, and at present complicated, holders are sometimes acceptable where the drill holder is adjusted only occasionally from one type of drill 4to another and a large number of drills of a single type and size are then utilized with a given setting of the holder. However, in many shops a wide variety of drills having various size and shape characteristics are often used from ytime to time but only a few of such drills `are used at any one time. Therefore, it becomes highly desirable to provide a drill holder which can be rapidly and easily adjusted to accommodate itself t-o drills of `a Wide variety of shapes and sizes but wherein the provision of ready adjustability in such a drill holder will not render it either unduly expensive to make, unacceptably complicated to use, or incapable of holding a drill accurately in a predeterminable position.

Accordingly, in designing -a drill holder directed toward the aforementioned general objectives, the more specilic objects and purposes of the invention are the following:

(l) To provide a twist drill holder, as aforesaid, which will hold the twist drill snugly and rmly in -a predeterminable position for grinding same.

(2) To provide a twist drill holder, as aforesaid, which will be readily and accurately adjustable to hold and accurately present to a grinding device drills having -a variety of dilferent lengths, diameters, relief angles, point angles and other characteristics.

(3) To provide a holder for a twist drill, 'as aforesaid, which will be capable of accurate adjustment for holding la drill of one ltype or for holding a drill of another type and wherein such adjustment can he made easily and quickly.

(4) To provide a holder for a ltwist drill, as aforesaid, wherein the aforesaid adjustments will be available without sacrificing accuracy and/or firmness of holding the 3'? E $13945 Patented 0st. 22, 1963 drill in the desired position with respect to a grinding wheel.

(5) To provide a holder for a twist drill, as aforesaid, having the adjustability mentioned above without sacrificing Aaccuracy and which will be capable of such adjustability without involving such an excessive cost as to make the holder unavailable as ya practical matter to plants having limited but necessary use for special type drill points.

(6) To provide a holder for a twist drill, as aforesaid, Which will be adaptable equally to conventional grinding and to ielectrolytic grinding.

(7) To provide a holder for a twist drill, as aforesaid, which will be adapt-able to use with electrolytic grinding machines and wherein the electrical contacts between the relatively movable parts thereof are sufficiently effective that the point of electrical connection to said holder may be spaced a substantial distance from the actual workpiece itself, whereby to relieve the operator from the inconvenience of having electrical wires and/0r cables in his way in the manipulation of the drill holder as would otherwise be true if the wires or cables wene connected directly to the drill being ground.

(8) To provide a twist drill holder, as aforesaid, wherein the foregoing named objects are accomplished while maintaining a holder which is easily and accurately counterbalanced in order to make it easy to operate over long periods of time without `appreciable operator fatigue.v

(9) To provide a twist drill holder, as aforesaid, which will be strong and sturdy and capable of maintaining its accuracy over a long period of rigorous use.

l (10) To provide a twist drill holder, as aforesaid, having relatively few parts and wherein said parts are of relatively simple construction in order -to minimize the cost of said holder and to maximize its sturdiness Iand reliability.

Other 'objects 4and purposesY of the invention Will be apparent to persons acquainted with devices yof this general type upon reading the following description and inspecting the accompanying drawings.

In the drawings:

FIGURE l is an oblique View of the ldrill holder of the invention shown in association with a drill held thereby `and 'a grinding machine for grinding said drill.

FIGURE 2 is an oblique view, taken from another angleyof the same subject matter as shown in FIG- URE 1.

FIGURE 3 is a `sectional view taken on the line III--III of FIGURE 2 and indicating in broken lines another position of the sector housing.

FIGURE 4 is a fragmentary sectional view taken on the line IV-IV of FIGURE 3.

FIGURE 4a is a sectional view taken on the line IVa-IVa of FIGURE 4.

FIGURE 4b is a sectional View taken on the line IVb-IJb of FIGURE 4.

FIGURE 5 is a section-al view taken on the line V-V of FIGURE 4.

FIGURE 6 -is a sectional view taken on the line VI-VI of FIGURE 2.

FIGURE 7 is a sectional View taken on the line VII--VII of FIGURE 6.

FIGURE 8 is a partially sectional view taken on the line VIII-VIII of FIGURE 2, but with :the lip guide removed.

FIGURE 9 is a plan view of the sector removed from the sector housing.

FIGURE l0 is a view of the sector taken from the left end -thereof as same appears in FIGURE 9.

FIGURE l1 is a sectional view taken on the line XI-XI of FIGURE 9.

FIGURE l2 is a side view of the sector housing with the sector and lip guide both removed.

FIGURE 13 is an end elevational view of the sector housing taken from the right side thereof in FIGURE 12.

FIGURE 14 is a side view of the sector housing taken from the reverse side with respect to that shown in FIGURE 12.

FIGURE is a sectional view taken in the line XV-XV of FIGURE 12.

General Description In general the invention comprises a swing plate held for rotation about a substantially horizontal swing axis, which axis passes approximately through the end of the drill when same is held in grinding position. A drill holder is mounted upon an arcuate segment, which segment is received within a sector housing and which is adjustable about a center located near the point of such drill. The sector housing is pivotally mounted on the swing plate `for adjustment in a direction perpendicular to the swing axis. Eccentric means are provided for effecting such` adjustment of said sector housing about said pivot with respect to said swing plate whereby the drill point is moved suitably with respect to the grinding wheel to provide varying relief angles thereon as desired.

Arcuate adjustment of the drill holder ywith respect to the sector housing is provided to vary the point angle of the drill. Movement of the entire assembly around the axis upon which the swing plate is mounted effects the desired presentation of a given drill lip to the grinding wheel.

Detailed Description `In describing the specific embodiment herein chosen for illustrating the invention, certain terminology will be used for convenience which will be recognized as being employed for convenience only and as having no limit ing significance. For example, the terms upwardlyl and downwardly will refer to the illustrated embodiment in its normal position of use. The terms leftward and rightward will refer to directions with reference to a drawing with respect to which such terminology is used. The terms inward `and outward will refer to directions toward and away from the geometric center of the apparatus. The terms forward and rearward will refer to the directions toward and away from the Ilocation occupied by the operator during normal operation of the apparatus, namely, toward or away from the side of the apparatus shown in FIGURE 1. Further, all of the terminology above defined include both derivatives of the words specifically mentioned and Words of similar import.

Turning now to the drawings, there is provided a base 1 adapted to be mounted upon any suitable support, not shown. The base in this embodiment is provided with a motor support 2 which in turn supports a motor 3 upon whose shaft is arranged a grinding Wheel 4, here a peripheral type wheel. A wheel guard 5 of any suitable type is mounted over the wheel in a conventional manner. It -will be understood, of course, that this mounting of the grinding wheel is only representative iof any conventional mounting `for a suitable grinding wheel and the particular means shown will be recognized as being merely illustrative and not limiting.

Turning now to the ygeneral organization of the drill holder, its supporting member 6 is mounted upon the machine base 1 and supports a swing structure 7 which in turn supports a sector housing 8. An arcuate sector 9 is supported within said sector housing 8 and in turn supports the drill carrier 11.

Referring to FIGURES 6 and 7, the supporting member 6 in this embodiment includes a pair of uprights 12 and 13 mounted on the base 1 and which support bearings 14 and 16. Said bearings support a shaft 17 rotatably therebetween, said shaft being rotatable by any convenient `manually operable means, such as the crank 18. The axis of shaft 17 is parallel with and is spaced appreciably below the axis of the grinding wheel 4. A portion of said shaft, indicated at 19, is provided with screw threading for purposes described hereinafter.

Around the shaft 17 is arranged a sleeve 21 which has end closures 22 and 23 provided for supporting said sleeve on said shaft. If desired, bellows structures may be provided as indicated on broken lines at 24 and 26 for keeping dirt and dust away `from said shaft.

An opening 27 is provided through a portion of the sleeve 21 which opening has ya follower 28 slidably disposed therein at the bottom thereof. A closure 29 is threaded into the top opening 27 and a spring `30 is provided ybetween said closure and the follower 2S for urging said follower downwardly against the threads 19. The lower end of the follower 28 is grooved for fitting around the threads of portion 19. Thus, ras the shaft 17 is rotated, it will act through follower 28 to effect axial movement in one direction or the other of the sleeve 6 according to the direction lof rotation of said shaft.

The sleeve 21 has a platform 31 allixed thereto, in this embodiment said platform being integral with said sleeve. An adjustable screw 25 mounted on said platform bears against an actuator 3), which in turn mounted rigidly on a shaft 33, said shaft being pivotally mounted in any convenient manner with respect to the base 1, such as by a bracket indicated schematically at B. Said shaft is rotated at the will of an operator in any desired manner such as by a foot treadle T (FIGURE 2) mechanically connected by suitable linkage L to said shaft. A stop 32, here shown as a flange, extends from the machine base 1 upwardly toward the actuator 30. This limits the rotation of the sleeve 21 in a counterclockwise ydirection as seen in FIGURE 7. A spring 34 is arranged under the actuator 30, bears against said actuator and acts through it and the screw 25 to urge the platform 31 upwardly. Thus, the platform 31 is normally held above the end of the stop 32 by the spring 34 but said platform 31 is able to move downwardly against said spring to -a limit determined by the combination of said screw 25 and said stop 32 and a `downward pull on the linkage L will in this embodiment act through the actuator 30 and screw 25 to lift the platform 31 upwardly around the sleeve 21.

`Referring lto FIGURES 1 and 2, the swing structure 7 comprises a casing 36 and a base 37. Said base comprises a pair of legs 38 and 39 which extend downwardly from the easing 36 and are supported upon a plate 41 which is fastened in any convenient manner, such as by bolting, to the platform 31. Referring to FIGURE 4, the casing 36 contains suitable bearings 42 and 43 therewithin which bearings are preferably of a preloaded type to minimize deflection. A cap 44 closes one end of the casing 36. A relatively heavy swing shaft 46 is supported within and rotatably by the bearings `42 and 43 in such a position that its axis may be parallel with the radial elements of the portion of the drill being ground at a given time. In this embodiment the shaft 46 carries a stepped disc 47 on the end thereof adjacent the grinding wheel 4. Said `disc 47 has an annular swing plate 48 mounted thereon, such as by pressing said disc 47 into a suitable opening 49 within said plate.

A ring 51 is snugly but rotatably mounted upon the casing 36, in this embodiment by causing same to be received against a shoulder 52 on said casing. Said ring 51 has an extension 53 (FIGURES l and 3) thereon extending toward and over an adjoining ring 54 which is also mounted on and supported by the casing 36. A set screw (FIGURE 2) 56 permits rotative adjustment of the ring 54 with respect to the casing 36 but thereafter functions to hold the ring 54 against rotative movement with respect to the casing 36. The ring 54 has a pair of stops 57 and 58 (FIGURE 3) extending radially outwardly therefrom and spaced from each other circumferentially, in this embodiment a :distance of one quarter of the circumference of the rin-g 54. As appearing in FIGURES 1, 2 and 3, the extension 53 of the ring 51 extends into a position circumferentially between the stops 57 and 58.

Returning now to the swing plate 48, there is provided in fixed and edgewise relationship thereto a sector housing 8 having an arcuate slot 62 (FIGURES 4 and 14) therein. This sector housing and slot 62 cooperate with means described further hereinafter for selecting the point angle to be provided on the drill being ground.

Referring to FIGURE 4, said sector housing S is pivotally aiiixed to the swing plate 48 by a screw 63 passing through said plate 4S and received into a threaded hole 64B in the sector housing 8. The head 64 of said screw extends into a Zone circumferentially between the stops 57 and 58 'for purposes appearing hereinafter.

The sector housing 8 is further related to the swing plate 4S by relief adjustment means 66 (FIGURE 4) which cause it to pivot slightly with respect to the swing plate 4S around the screw 63. A cam member 67 is provided with a flange 68 and Ian eccentric hub 69' which is disposed within an appropriately shaped opening in swing plate 48. An opening 71 extends through said cam member 67 and a somewhat elongated, generally coaxial, opening 72 extends therefrom through a portion of the sector housing 8 into a cavity 73. A connecting in means 74, here shown as a blo-lt, extends through the open-ings 7l and 72 and is fastened in place |by a suitable holding means, here indicated as a nut 76. The center of rotation of Ithe hub 69 is offset with respect to the axis of the connecting pin 74 in a direction which is substantially on a line connecting the axis of the pivot 63 with the axis of the connecting pin 74. Thus, small angular movement of the eccentric device 67 will move the connecting pin 74 a short distance substantially perpendicularly with respect to the line connecting the pivot 63 and the connecting pin 74. lf desired, a handle 77 may be provided for manually applying an accurately controlla'ole angular movement to the cam member 67. Thus, as cam member 67 is caused to move angularly, the sec-I tor housing 8 Iw'ill be caused to move about the pivot 63 with respect to swing plate 48 and the portion thereof adjacent said relief ladjustment mechanism 66 will move in a direction substantially parallel with the tangent to the :grinding wheel at the point of contact by the work being lground.

The sector member 9 has a body section `8l and an arcuate segment 82 extending sidewardly therefrom. Said segment 8,2 is received within the arcuate slot opening 62 in the sector housing 8 for angular adjustment therein. An opening 83 is provided through the housing 8 to permit observation of a scale 84 (FIGURE 4) appearing on the arcuate segment $2. A screw S6 extends through an opening in the sector housing 8 'and thence through an arcuate slot 8@ in segment 82. A nut SS is threaded `on screws 86 `and is non-rotatably disposed in an enlarged portion 99 of slot 36. Thus, the opposed portions of the plate 8 and the segment 82 may be tightened together and thereby the arcuate segment 82 may be fixed rmly in a selected location.

A pair `of rods S7 and 38 extend parallel =with respect to each yother from the body section 8l and in turn slidably support `a conventional drill holder S9 and a tailstock 91. In this particular embodiment, the holder 89 is arranged in a conventional ymanner to permit manual movement of said holder 89 along said rods upon loosening of the knob 92. Tightening of said knob 92 secures the holder 39 rigidly in place. The tailstock 9d is provided with a similar knob 93 which when loosened permits the tailstock ill to be slid along said rods and when tightened holds same `firmly in place. The tailstock 9i supponts, in this embodiment, a micrometer unit 94 lwhich upon adjustment of the knob 9i) will move the ram h5 thereof to determine the point of support of the shank end of the drill being sharpened and to feed the drill during the Agrinding operation.

Suitable shaping of the edge 96 of the body section 81 together with conresponding shaping `of the edge 97 of the holder S9 is provided for receiving and holding a drill in position as shown. In this embodiment a V- shaped groove is used, the details of which are well known to the industry and hence need no further description here.

A lip rest 99 is provided and -this includes a slidable bar 19d which in turn is selectively held in position in a groove i60 (FIGURES Sand 12) by a clamp 102, said clamp 'being tightened and loosened by a knob v103. The bar 10i carries a locating finger 165. Thus, the lip rest 99 may be positioned to properly locate the various diameter drills in the correct index position for grinding.

The overall geometry of the drill holder above described follows lthe presently known drill grinding arrangement which is designated in the art las utilizingr the inside of the developed cone, the same being well known to those skilled in the art and hence needing no further description. Accordingly, it is suicient to say here the axis of the shaft 46 passes through the center of rotation of the segment 32 and that the center line of the drill being ground passes below the extended axis of the shaft 46 a distance determined by the setting lof the relief mechanism 66, which in turn is determined by the amount of relief desired `on the drill.

A counterweight 106 (FGURES l and 2) is mounted, preferably adjustably, on a rod 107 which in turn is xed to the upper end of the sector housing 8. The adjustment of the counterweight is such as to enable the sector lhousing 3, the sector 9 and the tool carrier -111 all to swing relatively easily about the axis of the sli-aft 46 (FIGURE 4) for the purpose of swinging the drill to be sharpened lwith respect to the grinding wheel in a known manner.

Operation The operation of the drill holder of the present invention is sufficiently similar to the operation of 4presently known drill holders that it will be readily understood by those skilled in the art. However, certain of its features will require special consideration. Further, the apparatus is sufficiently versatile that it can be operated in any of several 'ways according Ito the wishes of the operator; nevertheless one typical procedure will be set forth to il-lustrate the invention.

(a) The screw S6 is loosened and the sector member 9 is moved with respect to the sector housing 8 untilwthe proper angle shows through the window 82+, thereby indicating that the proper point angle will |be formed by operation of the grinding Wheel. The screw 86 is then -re-tightened.

(b) The relief adjusting device 66 is then adjusted by movement of the handle 77 by which the lower end of the sector housing S is moved about the pivot screw 63- in a direction substantially perpendicular to the plane of said sector housing. This moves the poin-t of the drill in the same direction with respect to the axis o-f the shaft 46 and thereby effects adjustment of the relief angle provided on the drill. Preferably the flange portion 68 of said relief angle adjusting cam member 6-7 will be marked with suitable graduations indicating the character and amount of the relief angle so provided.

(c) A drill D to be sharpened is placed within the sliding holder 39 and allowed to rest against the ram portion 9S of the tailstock 9i..

(d) The locating linger (FIGURE l) is moved into position in yfront of the drill and the drill is moved thereagainst to position its point in `the proper position with respect to the axis of the shaft 46.

(e) The micrometer unit 94 on the tailstock 91 is then operated to move the ram 95 against the shanl; of the drill to hold the drill inthe desired position.

(f) Next, the adjustable ring l ywill be positioned by first loosening the thumb screw 55 and rotating the ring 51 until the extension 53 thereof is in the desired position between the stops 57 and 53 of the ring 54. This limits the amount of rotation of the drill holder mechanism about the axis of the shaft ftd, wlich amount will be chosen in a known manner according to the number of lips on the drill.

(g) Lastly, the crank i3 will `be operated to move the entire assembly in a direction ardally of the shaft i7 whereby to position the drill lip in proper axial alignment with the peripheral face of the grinding wheel 4.

While the above adjustments have been described in one preferred order for illustrative purposes, it will be recognized by those skilled in the art that many of the several adjustments are independent of euch other insofar as the order in which they are performed is concerned and accordingly no limitation is intended by the statement or" said adjustment steps in the particular order above given. Other sequences of such adjustments are possible and will in many cases be preferred by other operators or may be required according to the kind of `drill 4being ground.

With the adjustments now made, the operator may hold the drill against the body part 81 and holder S9 by his left hand (or the `drill may if preferred he held in place by a conventional clamp, not shown) with his right hand on the micrometer feed knob Qt) to operate same. The operator then raises the drill holder around the axis of swing shaft 46 to an approximately horizontal position and simultaneously actuates the treadle T to lower the actuator 39 and permit the entire apparatus to rotate `under its own weight around the axis of the shaft 17. This moves the drill into grinding position against the wheel 4. With the drill properly bearing against the lgrinding surface of the wheel 4 the operator will effect the usual swinging of the sector housing S and the parts carried thereon around the axis of the swing shaft 46 to present to the grinding wheel of the entirety of one land of the drill being ground including the lip portion thereof. When one land is thus ground, the drill holder is permitted to respond to the pressure of the spring 3d and return into its inactive position. The drill is then rotated to place the next lip into position for grinding, the same being again aligned and the same operations as above described are repeated for grinding of the second lip and land associated therewith excepting that he will now leave the micrometer in its last position and use only the foot treadle for feed purposes. As the operator acquires skill, he may eventually use the foot treadle also for other feed purposes.

lf there are more than two lands on the drill the -foregoing described operations are repeated for each land until all lips and lands of the drill are satisfactorily ground.

The wide areas of Contact between the sector 9 and the sector housing 8 makes possible a suliiciently good electrical contact therebetween that good electrical conductivity will be obtained even at the low voltages used in electrolytic grinding operations. This ermits the supply cable for electrical potential when an electrolytic grinding operation is Kbeing performed to be applied to the sector housing 3 rather than to the drill itself or to the sector 9. Thus, the electrical supply cable is out of the operators Vway as he operates the apparatus.

Although a particular preferred embodiment of the invention has Ibeen disclosed above in detail for illustrative purposes, it will be understood that variations or modifications of such disclosure, which lie within the scope of the lappended claims, are fully contemplated.

What is claimed is:

l. A drill grinder comprising:

a base;

a grinding element movably supported on said base and means for moving said grinding clement, said grinding element having a grinding surface;

mounting means and support means rotatably supporting said mounting means for rotation about a tirst axis which extends at an angle to said grinding surface;

means on said Ibase mounting said support means for movement in a direction transverse to said grinding surface;

housing means mounted on said mounting means for pivotal movement about `a second axis parallel with `and offset from said yfirst axis;

manually operable actuating means for selectively moving said housing means with respect to said mounting means about said second axis, said housing means otherwise being rotatable with said mounting means, said actuating means including an eccentric means connecting said housing means to said mounting means for effecting said pivotal movement of said housing means with respect to said mounting means;

said housing means having an arcuate guide means located near said grinding surface and disposed about an axis of arcuate movement which is perpendicular' to said tirst axis and which is located close to said lirst axis and said grinding surface;

`an arcuate segment located adjacent said grinding surface and slidably mounted in said arcuate guide means for arcuate movement about said axis of arcuate movement;

a drill holder mounted on said arcuate segment and defining an elongated, drill-receiving guide extending crosswise of said arcuate segment toward said first axis and said axis of arcuate movement, the longitudinal axis `of said guide extending transverse to and intersecting said grinding surface so that the point cf ya drill disposed in said guide can engage said grinding surface.

2. A drill grinder as set forth in claim l, in which said housing means has a groove therein;

a bar slidably disposed in said groove and extending closely adjacent said grinding surface, said bar being extendable `across the adjacent end of said drill 'holder for locating the tip of the drill with respect to said grinding surface.

3. A drill grinder as dened in claim 1 in which said means on said base mounting said support means for movement comprises a support shaft mounted on said base below said grinding surface and extending substantially parallel with said grinding surface, a plate mounted on said support shaft for pivotal movement around the axis thereof and for axial movement thcrealong, and means on said plate connected to said support means.

4. A drill grinder as defined in claim 1, in which said grinding ele-ment is a grinding wheel and said grinding surface is the periphery of said grinding wheel and in which said drill holder includes drill support means delining an elongated drill receiving recess at one end of said arcuate segment which extends substantially radially toward the axis of arcuate movement of said arcuate segment and transverse to the periphery of said grinding wheel, and an adjustable tail stock close to the radially outer end of said drill support means for engaging the chuck end of a drill and holding it in an adjustable position with respect to said periphery of said grinding wheel.

5. A drill grinder as deined in claim l wherein said axis of arcuate movement is substantially parallel with the direction of movement of said housing vmeans with rcspect to said mounting means.

6. A drill grinder as defined in claim 1, wherein said first axis extends at an acute angle to said grinding surface and intersects said axis of arcuate movement of said arcuate segment.

7. A drill grinder as defined in claim l, wherein said 9 mounting means is secured to a s-wing shaft rotatably mounted in said support means;

Stops adjustably xedly mounted on said support means; and

pin means on said mounting means and engageable `with said stop means -ior limiting rotation of said swing shaft with respect to said mounting means.

8. A drill grinder comprising:

a base;

a grinding element mow/ably supported :on said -base and means lfor moving said grinding element, ysaid grinding element having a grinding surface;

a rotatable swing shaft and a support therefor;

means on said base mounting said swing shaft support for movement in a direction transverse to said grinding surface;

mounting means aiiixed to said swing shaft;

ihousing means mounted on said mounting means for pivotal movement with respect thereto about an axis parallel with and offset from said swing shaft `axis and in a direction substantially perpendicular to the axis of said swing shaft;

manually operable actuating means for selectively movying said housing means with respect to said mounting means in said direction, said housing means otherwise being rotatable with said swing shaft, said actuating means including an eccentric extending into said housing means and means supported in said mounting means for rotating said eccentric;

said housing means having arcuate guide means located in front fof said grinding surface and disposed about an axis of arcuate movement which is perpendicular to the axis of said swing shaft and which is located 1) close to said swing shaft axis and said grinding surface;

an arcuate segment located adjacent said grinding surface and slidably mounted in said arcuate guide means for arcuate movement about said axis of arcuate movement;

a drill hol-der mounted on ysaid arcuate segment for holding an elongated drill so that its longitudinal axis extends crosswise of said arcuate segment toward Vsaid swing shaft axis and said axis of arcuate movement with its point adjacent said axis of arcuate movement and said longitudinal axis of said drill also extending transverse to said grinding surface from in front toward the rear thereof and intersecting said grinding surface so that the point of the drill can engage said .grinding sur-face, the angle which the point of said drill makes with said grinding surface being adjustable #by changing the position of said arcuate segment in said arcuate guide means and the relief angle ground lon said drill being adjustable by moving said housing means with respect to said mounting means.

References Cited in the file of this patent UNITED STATES PATENTS 2,369,642 Benning Feb. 20, 1945 2,600,432 Sanders June 17, 1952 2,647,352 Laniberty Aug. 4, 1953 2,797,533 Bluemink July 2, 1957 FOREIGN PATENTS 111,433 Great Britain Nov. 29, 1917 1,206,734 France Feb. 11, 1960 

4. A DRILL GRINDER AS DEFINED IN CLAIM 1, IN WHICH SAID GRINDING ELEMENT IS A GRINDING WHEEL AND SAID GRINDING SURFACE IS THE PERIPHERY OF SAID GRINDING WHEEL AND IN WHICH SAID DRILL HOLDER INCLUDES DRILL SUPPORT MEANS DEFINING AN ELONGATED DRILL RECEIVING RECESS AT ONE END OF SAID ARCUATE SEGMENT WHICH EXTENDS SUBSTANTIALLY RADIALLY TOWARD THE AXIS OF ARCUATE MOVEMENT OF SAID ARCUATE SEGMENT AND TRANSVERSE TO THE PERIPHERY OF SAID GRINDING WHEEL, AND AN ADJUSTABLE TAIL STOCK CLOSE TO THE RADIALLY OUTER END OF SAID DRILL SUPPORT MEANS FOR ENGAGING THE CHUCK END OF A DRILL AND HOLDING IT IN AN ADJUSTABLE POSITION WITH RESPECT TO SAID PERIPHERY OF SAID GRINDING WHEEL. 